1. Technical Field
This invention relates to a damper mechanism for generating an effect of damping impact by utilizing the pressure drag of a highly viscous functional oil.
2. Prior Art
A damper mechanism utilizing a functional oil as a damping medium as illustrated in illustrated in FIG. 5 of the accompanying drawings is already known.
The damper mechanism of FIG. 5 comprises a cylinder a, a blade shaft b disposed along the axis of the cylinder a, a blade c filled to the outer peripheral surface of the blade shaft b and designed to slidingly move on the inner peripheral surface of the cylinder a, an upper stationary bearing (not shown) and a lower stationary bearing (not shown) for rotatably holding the blade shaft b, a stationary blade g arranged outside the blade c and a nonreturn valve i disposed in an oil passage h running through the stationary blade g, the inside space d of the cylinder a being divided into two chambers A, B by the blade c, both of the chambers A, B being filled with a functional oil e.
If a relatively large gap exists between the inner peripheral surface a' of the cylinder a and the blade c of a damper mechanism illustrated in FIG. 5, the functional oil e can leak through the gap at an enhanced rate to reduce the damping effect of the mechanism when the blade shaft b is rotated. If, on the other hand, no gap exists therebetween, the blade c becomes incapable of moving smoothly within the cylinder a.
For a damper of the above described type, therefore, there always arises a requirement of reconciling the prevention of leakage of functional oil e and the smooth movement of the blade c.
In order for the requirement to be met, the inner peripheral surface a' of the cylinder a, the blade shaft b, the blade c and other metallic parts of a conventional damper mechanism are subjected to precision machining and precision assembly so that the gap may be made as small as possible.
Obviously such measures can, by turn, pose technical difficulties in machining and assembly of metallic parts and components of the damper mechanism.
Additionally, a conventional damper mechanism as described above is accompanied by the problem of poor durability due to the fact that friction inevitably occurs between the inner peripheral surface a' of the cylinder a and the blade c as the latter slidingly moves on the former until they are abraded and no longer able to operate on a stable basis.
An alternative measure that has been proposed for the prevention of leakage of function oil e consists in providing the blade c with a lining member f and a sealing member.
With such a proposed technique of using a lining member f and a sealing member, the level of precision machining and assembly of metallic parts and components may apparently be reduced.
Such a technique, however, is accompanied by the problem of early abrasion of the lining member f and the sealing member at locations where they are held in contact with the inner peripheral surface a' particularly when the surface a' is coarsely finished.
Therefore, the proposed technique cannot satisfactorily provide a prolonged stability and an enhanced durability of a damper mechanism under consideration.
An additional cost will be involved in the manufacture of a damper mechanism as illustrated in FIG. 5 when an oil passage h is bored through the stationary blade g of the cylinder a and a nonreturn valve i is arranged at the oil passage h.